You can legally drive it to a garage for work to get it through it's MOT as long as you are insured. You can't get tax until the MOT is done, but the plod can still stop you if they think the car is unsafe.
you MUST have an appointment at the garage though go straight there and straight back. I guess this is to stop people driving around with no MOT and then getting stopped and say "I am just on my way to the garage........"
just be sensible and safe